Larkiola, Jari

Nylander, Jari

Verho, Martti

The discontinuous cold rolling process has some major disadvantages compared to continuous / coupled cold rolling mills. The usual bottle neck of the process is linked to the amount of the strip thread-in/out, so rolling efficiency is mainly controlled by the success in threading control. Setup calculation models should also be able to calculate accurate values into the wide range of steel grades in different velocity phases and process conditions. To reach better rolling stability and product constancy, lubrication aspects appear to be a key issue which is necessary to control better in order to prevent abnormal working conditions in the roll gap. In this work, a monitoring system for the 4 stand cold rolling process is created. The program reads strip related data from the automation system after the coil has finished in the exit section of the tandem mill. This input data is used, e.g. to calculate material flow stress curve and friction values of the stands. Furthermore, different velocity phases including threading in, low speed, acceleration, run speed and deceleration are taken into account during the analysing process. Results are stored in the database and by utilising the query options of the monitoring system the user can get a graphical view of the desired outputs. The monitoring system is used to improve pass schedule calculations by solving required process parameters. In addition, the processibility of the new steel grades can be predicted more accurately by utilising monitored results of the material flow stress curves. This speeds up, e.g. the development work of the new steel product and shortens the time from enquiry to trial and further on to the customer delivery. Also, dimensional ranges can be extended using more exact process parameters defined by analysing system

Monitoring of process variables and friction during cold rolling

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